Update proto generation commands to the most recent and update README. (#589)

* Update protoc commands to the most recent and update README.

Followed instructions at https://developers.google.com/protocol-buffers/docs/reference/go-generated.

Additional Testing:
- `go generate ./...` works.

Author: wenovus

demo/protobuf_getting_started/ribproto/openconfig/enums/enums.pb.go

@@ -9,9 +9,10 @@ syntax = "proto3";
 
 package openconfig.enums;
 
-import "github.com/openconfig/ygot/proto/ywrapper/ywrapper.proto";
 import "github.com/openconfig/ygot/proto/yext/yext.proto";
 
+option go_package = "github.com/openconfig/ygot/demo/protobuf_getting_started/ribproto/openconfig/enums";
+
 // OpenconfigBgpTypesAFISAFITYPE represents an enumerated type generated for the YANG identity AFI_SAFI_TYPE.
 enum OpenconfigBgpTypesAFISAFITYPE {
   OPENCONFIGBGPTYPESAFISAFITYPE_UNSET = 0;

demo/protobuf_getting_started/ribproto/openconfig/enums/enums.proto

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package openconfig_enums is a protobuf package that is generated by
+// Package enums is a protobuf package that is generated by
 // ygot. This file ensures that build systems that assume the existence
 // of the package can find it.
 
-package openconfig_enums
+package enums

demo/protobuf_getting_started/ribproto/openconfig/enums/pkg.go

@@ -9,10 +9,11 @@ syntax = "proto3";
 
 package openconfig;
 
-import "github.com/openconfig/ygot/proto/ywrapper/ywrapper.proto";
 import "github.com/openconfig/ygot/proto/yext/yext.proto";
 import "github.com/openconfig/ygot/demo/protobuf_getting_started/ribproto/openconfig/openconfig_rib_bgp/openconfig_rib_bgp.proto";
 
+option go_package = "github.com/openconfig/ygot/demo/protobuf_getting_started/ribproto/openconfig";
+
 message Device {
   openconfig_rib_bgp.BgpRib bgp_rib = 314942212 [(yext.schemapath) = "/bgp-rib"];
 }

demo/protobuf_getting_started/ribproto/openconfig/openconfig.pb.go

@@ -13,6 +13,8 @@ import "github.com/openconfig/ygot/proto/ywrapper/ywrapper.proto";
 import "github.com/openconfig/ygot/proto/yext/yext.proto";
 import "github.com/openconfig/ygot/demo/protobuf_getting_started/ribproto/openconfig/enums/enums.proto";
 
+option go_package = "github.com/openconfig/ygot/demo/protobuf_getting_started/ribproto/openconfig/openconfig_rib_bgp";
+
 message BgpRib {
   message AfiSafis {
     message AfiSafi {

demo/protobuf_getting_started/ribproto/openconfig/openconfig.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package openconfig_openconfig_rib_bgp is a protobuf package that is
+// Package openconfig_rib_bgp is a protobuf package that is
 // generated by ygot. This file ensures that build systems that assume the
 // existence of the package can find it.
-package openconfig_openconfig_rib_bgp
+package openconfig_rib_bgp